Toilets which use conventional water flush apparatuses are a typical example of waste, the quantity of water used to obtain effective flushing of the bowl often being disproportionate to the actual needs of the users.
A certain number of manufacturers have therefore included in their range double-release water flush apparatuses which allow the user to employ a partial or a complete cistern. In order to market effective water flush apparatuses, the manufacturer is obviously obliged to provide a maximalist solution which ensures an effective result whatever the conditions of use.
It is therefore difficult if not impossible to adapt each WC to the individual requirements of each household. Moreover, the dual control is seldom easy or obvious in its operation. The only real possibility of control left to the user is that of controlling the maximum level of the cistern, something which is possible only to a relatively small extent. Moreover, once the level of the water has dropped, the centre of gravity of the mass of water is displaced downwards, resulting in a reduction in the potential energy accumulated in the cistern and a consequent loss of efficiency.